Loud-speaker



7, 1965 M. 1'. BASSECHES 3,200,901

LOUD-SPEAKER Filed April 20, 1964 INVENTOR United States Patent3,200,901 LOUD-SPEAKER Mark T. Basseches, @ld Farm Road 8.,Pleasantville, N.Y. Filed Apr. 20, 1964, Ser. No. 360,999 3 Claims. (Cl.181-32) This invention relates to a loud-speaker device, and moreparticularly to a novel loud-speaker device having particular utility inreproducing, with minimum distortion, frequencies within the audiorange.

Still more particularly, this invention relates to a transducer devicewhereby impressed electrical signals of a given amplitude and frequencycause concomitant movements of a radiating diaphragm to cause saiddiaphragm accurately to translate electrical input signals and to movein accordance with the frequency and amplitude of the impressed signals.

Still more particularly, this invention relates to a high fidelityloud-speaker device wherein the vibratory motion produced by atransducer having a diaphragm or driver input surface is hydraulicallytransmitted to a large radiating diaphragm, to cause such largediaphragm to move as a unit at the frequency of the transducer andthrough an amplitude proportionately smaller than the first mentioneddiaphragm or input surface.

Modern loud-speakers may be divided into two classes. The first class isknown as the magnetic speaker and incorporates, typically, a highintensity magnetic field. A voice coil is movably suspended in the fieldand is connected to a radiating one, usually comprising papiermache, andmore recently expanded polyurethane foam. The voice coil is connected tothe apex of the cone, the rim of the cone being movably suspended to aframe. Electrical signals in the audio range (about 25 to 20,000 cyclesper second) are impressed on the voice coil, generating a magnetic fieldof varying nature, depending upon the signals. The reaction between thehigh intensity field and the field generated by the voice coil causes amovement of the voice coil and a consequent movement of the cone apex.The motion imparted to the cone apex in turn causes a movement of theentire cone resulting in the production of sound.

Other permanent magnet speakers include so-called horn type radiators inwhich a diaphragm other than a cone may be employed.

The second general class of speaker in common use is known as anelectrostatic speaker and consists of a conductive diaphragm suspendedin a polarized field. Audio signals are impressed on the conductivediaphragm, causing the latter to be attracted and repelled in accordancewith the impressed signal.

While the permanent magnet type speakers are in widespread use and arecapable of high quality reproduction of sound, certain drawbacks inherein the use of all such speakers heretofore known. Specifically, byapplying the moving force to the apex of the cone, there is introduced arelative movement of the various portions of the cone, with aconcomitant distortion of the emitted sounds.

Similarly, since both the front and rear surfaces of the cone are soundradiating surfaces, it is necessary to enclose or bafile the cone ty espeaker to phase the rear radiation with the front radiation, or,alternatively, to cancel out the effects of the rear radiation.

In either instance, to effect a phasing or cancellation of the effectsof the rear radiation, it is necessary that the speaker be mounted in alarge enclosure, with its accompanying high expense, waste of livingspace, and detraction from the general decor.

Electrostatic speakers, on the other hand, while capable of high qualitysound reproduction, are generally ex- 3,200,901 l atented Aug. 17, 1965tremely expensive because of the requirement to provide an apparatus togenerate the high polarizing voltages necessary for their operation.Additionally, electrostatic speakers for the reproduction of the fullaudio frequency range must be provided with extremely large radiatingsurfaces, since the reproduction of sounds, particularly in the lowfrequency range, requires the movement of considerable volumes of airand the amplitude of movement which may be achieved though the use ofthe electrostatic principle is extremely limited.

It is therefore an object of my invention to provide a high qualityreproducer of sound which overcomes many of the drawbacks of soundreproducing devices heretofore known.

A still further object of the invention is the provision of atransducing system which introduces a minimum of distortion orcoloration of the input audio signal.

Still a further object of the invention is the production of atransducer or loud-speaker system which is capable of high fidelitysound reproduction and which requires little or no bathing of thesystem.

Still a further object of the invention is the production of a highfidelity loud-speaker which operates on a hydraulic principle, whereby alarge radiating surface or diaphragm is caused to move as a unit, with aminimum of relative movement between the parts of the said diaphragm inresponse to movements of larger amplitude by a smaller input surface ordiaphragm.

Still a further object of the invention is to provide a device of theclass described which may occupy less space than units heretofore known,while providing higher quality sound reproduction, particularly in thelower audio range.

To attain these objects and such further objects as may appear herein orbe hereinafter pointed out, I make reference to the accompanyingdrawings, forming a part hereof, in which:

FIGURE 1 is a vertical crosssectional view of a loud speaker inaccordance with my invention;

FIGURE 2 is a vertical cross-sectional view of a further embodiment of adevice in accordance with my invention.

Referring now to the drawings, in FIGURE 1 there is shown a loud-speakerdevice 10 including a combined frame and fluid container 11. While theframe and container 11 are of generally conical configuration, it willbe readily understood that the particular configuration may be variedand, hence, should not be taken in a limitative sense.

At the apex portion 12 of the container 11, there is supported a more orless conventional transducer 13 which, in the illustrated embodiment,operates on the permanent magnet-voice coil principle. It will beunderstood by the skilled worker that substantially any transducerdevice capable of translating electrical impulses into mechanicalmovement may be employed and that the utility of the loud-speaker is byno means limited to use with magnetic voice coil transducers.

The transducer 13 includes a permanent magnet assembly 14, preferablygenerating a high flux within the 'cylindrical gap 15. Suspended withinthe gap 15, on a cylindrical mandrel 16, there is wound a suitable voicecoil 17 of an impedance which, in accordance with known practice, ismatched to the impedance of the output of the amplification systememployed. The mandrel or voice coil support 16 is secured at its forwardend 18 to an input diaphragm 19, which may also be referred to as apressure producing diaphragm or instrumentality.

The diaphragm 19 is movably mounted to the frame 11 by a cylindrical orannular spring suspension 20 which permits a relative movement betweenthe diaphragm and the frame 11, and which tends to reestablish aninitial cone speaker, there is no significant rearward positionalrelationship between the said diaphragm and the frame when moved fromits initial position. Preferably, the suspension is of the linear actingtype, i.e. within the range of movement calculated for the diaphragm,the restoring force exerted by the suspension 20 on the diaphragm issubstantially constant.

A radiating diaphragm 30 is secured to the rim 31 of the frame 11through the medium of a further suspension 32. It will be understoodthat the suspensions 20 and 32 may be comprised of resilient material,such as nylon, accordion pleated to permit excursions of the variousdiaphragms supported thereon. However, other forms of suspensions forthe diaphragms may be employed.

The space 33 between the diaphragms 19 and 30 is filled with arelatively incompressible liquid, such as a light hydraulic fluid, wateror the like. Preferably the space is entirely filled and there isprovided a drain and fill plug 34 through which the said fluid may beintro duced or removed. Optionally, sealing gaskets (not shown) may bedisposed between the diaphragms and the suspensions at all points whereleakage may occur or, alternatively, one or both of the diaphragms maybe formed integrally with the suspensions and/or with the container.

Leads 35, 36 of the voice coil are, in accordance with usual practice,connected to the output of an audio amplifier. I

It will be readily recognized from the foregoing that the electricalsignals impressed on the voice coil 17 will cause the mandrel 16 and,hence, the input diaphragm 19, to vibrate or move in accordance with theamplitude and frequency of the impressed signal. Since the volume withinthe container must remain constant, a movement of the diaphragm 19, forinstance, in the direction of radiating diaphragm 30, must becompensated for by a forward movement of the radiating diaphragm 30, thelatter movement being smaller than the movement of the diaphragm 19 inview of the larger area of the diaphragm 30.

When the diaphragm 19 shifts away from the radiator diaphragm 30, itwill be understood that such a movement would tend to increase thevolume of the container and that the radiator diaphragm 30 will movetoward the diaphragm 19, to maintain the volume at a substantiallyconstant level partially under the influence of the spring suspension32, where such a spring suspension is employed, and under the influenceof atmospheric pressure which bears against the outer surface of thediaphragm 30.

From the foregoing it will be appreciated that the inward and outwardmovements of the input diaphragm result in concomitant inward andoutward movements of the radiator diaphragm, the latter movements beingof a smaller excursions due to the increased area of the radiatingdiaphragm as compared with the input diaphragm.

It will be further observed that the hydraulic pressure exerted on theinner surface of the radiating diaphragm is applied equally over eachportion of the area of such diaphragm and the same therefore movessubstantially as a unit. Such unitary movement results in a smooth,substantially undistorted response, eliminating the harmonic andintermodulation distortions customarily occurring in cone type speakersdue to the break up or simultaneous movement in different directions ofvarious parts of the cone.

It will be further appreciated that there is no substantial requirementfor bafiling since, unlike the conventional tion.

It will be readily appreciated that while the system may sound radiabeutilized for full frequency range sound reproduction, it may be founddesirable, in certain instances, to provide a plurality or independentunits, and to divide the electrical impulses into frequency ranges, withthe appropriate frequency ranges directed to the proper units, dependingupon the resonance characteristics of the unit.

Further, it will be understood that a loud-speaker in accordance withthe invention may be used, for instance, as the woofer in a highfidelity system, with other component types providing the mid-range and/or tweeter response.

In certain instances it may be found desirable to dispose the radiatingdiaphragm and the input diaphragm in close proximate relation one to theother. In the embodiment of FIGURE 2, where like parts are given likereference numerals, the transducer 13a is disposed .entirely within thecontainer 11a, with portions of the rearward housing of the transducerbeing formed in common with the inner faces of the container 11a. In theembodiment of FIGURE 2, the input diaphragm 19a and the radiatingdiaphragm 30a are parti-spherical in configuration and areconcentrically disposed one to the other. This arrangement is highlydesirable in that a wide dispersion of sound is achieved, and thepossibility of phasing problems, which might result should the pressurereach one portion of the radiating diaphragm before it reaches otherportions, is eliminated.

The arrangement of FIGURE 2 is particularly desirable for thereproduction of the very high frequencies.

From the foregoing it will be recognized that there is disclosed aloud-speaker or transducer system which is capable of reproducing soundwith the highest fidelity, substantially free of the distortionencountered in heretofore known systems. Moreover, the ability toutilize the system without the requirement for baflling or enclosing thesame enables the production of loud-speaker systems of comparativelysmall size and high quality.

Having thus described my invention and illustrated its use, what isclaimed as new and is desired to be secured by Letters Patent is: l

1. A loud-speaker device comprising a sealed, liquid filled container ofsubstantially fixed volume, a relatively stifi radiating diaphragmforming a boundary of said container, a relatively stiif sound generatordiaphragm forming a second boundary of said container, said soundgenerator diaphragm being of lesser area than said radiator diaphragm,first and second flexible suspension means interposed between saidcontainer and said radiating and generator diaphragms, respectively, formounting said input and radiator diaphragms to said container to permitexcursions of said diaphragms relative to said container withoutsubstantial deformation of said diaphragms, and transducer meansconnected to said sound generator diaphragm for moving the latterresponsive to the amplitude and frequency of electrical impulses appliedto said trans ducer means.

2. A device in accordance with claim 1 wherein said input and radiatordiaphragms are coaxially disposed.

3. A device in accordance with claim 2 wherein said diaphragms areparti-spherical.

References Cited by the Examiner UNITED STATES PATENTS 1,297,206 3/19McLennan 181-32 1,451,422 4/23 Hahnemann 181--32 1,801,521 4/31 Milnorl81-27 1,862,582 6/32 Schlenker 18l--31 2,913,602 11/59 Joy 181-32 X LEOSMILOW, Primary Examiner. 7

1. A LOUD-SPEAKER DEVICE COMPRISINGA SEALED, LIQUID FILLED CONTAINER OFSUBSTANTIALLY FIXED VOLUME, A RELATIVELY STIFF RADIATING DIAPHRAGMFORMING A BOUNDARY OF SAID CONTAINER, A RELATIVELY STIFF SOUND GENERATORDIAPHRAGM FORMING A SECOND BOUNDARY OF SAID CONTAINER, SAID SOUNDGENERATOR DIAPHRAGM BEING OF LESSER AREA THAN SAID RADIATOR DIAPHRAGM,FIRST AND SECOND FLEXIBLE SUSPENSION MEANS INTERPOSED BETWEEEN SAIDCONTAINER AND SAID RADIATING AND GENERATOR DIAPHRAGMA, RESPECTIVELY, FORMOUNTING SAID INPUT AND RADIATOR DIAPHRAGMS TO SAID CONTAINER TO PERMITEXCURSONS OF SAID DIAPHRAGMS RELATIVE TO SAID CONTAINER WITHOUTSUBSTANTIAL DEFORMATION OF SAID DIAPHRAGMS, AND TRANSDUCER MEANCONNECTED TO SAID SOUND GENERATOR DIAPHRAGM FOR MOVING THE LATTERRESPONSIVE TO THE AMPLITUDIE AND FREQUENCY OF ELECTRICAL IMPULSES APLIEDTO SAID TRANSDUCER MEANS.